GPIO Protection¶

When implementing a custom carrier board/base board design for the MitySOM-335x series of modules all externally accessible GPIO signals should be protected from over-current and/or over-voltage conditions. Unless otherwise noted all AM335x pins that are accessible on the MitySOM-335x edge connector are DIRECTLY connected to the processor without any protection circuitry.

Table 4.1 of the AM335x datasheet lists the maximum buffer strength for each pin. For the GPIO signals they are either 4mA or 6mA. If active signal protection is not utilized (opto-isolators, buffers, level translators, etc.) then we recommend at least using ~1k ohm resistors in series with these external GPIO signals to limit the current draw for most protection cases. You may also want to consider adding ESD protection and/or a zener diode for input signals.

4mA Max GPIO Pins

gpio0[7,12,13,14,15,18,19,20]
gpio1[8,9,10,11]
gpio3[5,6,13]

All other GPIO max current source capability is 6mA